IELTS grammar: Common Spelling Mistakes

Spelling is graded explicitly, not incidentally: the Lexical Resource band descriptors specifically reference spelling accuracy as part of what separates higher bands from lower ones, which means a sophisticated, precisely chosen word that is then misspelled does not get full credit for that sophistication — the examiner has to weigh the accuracy alongside the ambition. The error pattern worth naming upfront is that spelling mistakes under exam conditions rarely come from not knowing how to spell a word; they come from time pressure, handwriting or typing speed, and a small set of specific words that are genuinely irregular or inconsistent in English spelling and therefore get misspelled even by strong writers who know the rule perfectly well when not rushing.

British and American English maintain two parallel, internally consistent spelling systems, and IELTS accepts either as long as it is applied consistently. The core pattern differences are worth knowing precisely rather than vaguely: British "-our" corresponds to American "-or" ("colour/color," "favour/favor," "labour/labor"); British "-ise" corresponds to American "-ize" for many verbs ("organise/organize," "realise/realize," "analyse/analyze" — though "analyse" additionally differs by an extra letter, "analyse/analyze"); British "-re" corresponds to American "-er" ("centre/center," "theatre/theater"); and British doubles a final "l" before a suffix where American often does not ("travelling/traveling," "cancelled/canceled"). Many common academic words are actually identical in both systems — "government," "necessary," "environment," "development" — so the consistency rule really only needs to be actively applied to the specific set of words that genuinely diverge between the two systems.

The consistency rule itself is simple to state but easy to violate under time pressure: pick one system at the start of the response and apply it throughout, rather than writing "colour" in one paragraph and "organize" in another. This matters more than which system is chosen — examiners are trained to accept both British and American spelling with no preference — but a mixed response signals carelessness rather than genuine bilingual competence, since a writer who has fully internalised one system rarely drifts into the other by accident partway through a response.

A specific set of high-frequency academic and Task 2 vocabulary words causes disproportionate spelling trouble, and they cluster into recognisable categories. Silent or unstressed letters cause errors in "government" (not "goverment"), "environment" (not "enviroment"), "different" (not "diffrent"), and "interesting" (not "intresting") — all words where an unstressed vowel in speech gets dropped in writing. Doubled consonants cause errors in "occurred"/"occurrence" (double "r"), "recommend" (double "m"), "embarrassed" (double "r" and double "s"), "accommodate" (double "c" and double "m"), and "necessary" (one "c," two "s"s — the reverse pattern from what many candidates guess). Suffix-related errors cause "definitely" to become the very common misspelling "definately" (it comes from "definite," not a nonexistent "definate"), "argument" to lose its final "e" from "argue" (correctly "argument," not "arguement"), and "truly" to drop the "e" from "true" (correctly "truly," not "truely").